Iodine has been used for water disinfection on a large scale in the past. Iodine is used commonly also for its antibiotic (sensu stricto) effects against bacteria, viruses and cysts, as these three pathogens constitute the most common health risks in maintaining biologically safe water supplies. Traditionally, crystalline iodine is dissolved in water under static conditions by the addition of small amounts of KI, which greatly enhances the dissolution of the iodine.
Of particular interest in a drinking water context, are those bacteria responsible for widespread occurrences and recurrences of intestinal infections in humans, namely, the coliform family of bacteria, e.g., E coli. These bacteria commonly contaminate drinking water supplies when waste water containing faecal material spills into a water supply, or when excessive anaerobic decay of vegetation in the water supply occurs. In general, the actual inactivation mechanism of the pathogenicity of both bacteria, viruses and cysts by iodine is poorly understood.
To-date, iodine is generally provided from an iodophor source or as an aqueous solution by the use of KI to aid the dissolution of iodine. Most treatments employ pHs lower or higher than about 9.
Dissolved iodine hydrolyzes in aqueous solutions to form hypoiodous acid, HOI, in amounts proportional to the pH of the solution, wherein above pH 8.5, iodine is present almost exclusively as HOI. Both dissolved I.sub.2 and HOI possess antipathogenic properties. At pHs 5-7, iodine, as I.sub.2, exhibits antibacterial action and at higher pHs, e.g. 7-10, HOI is an efficient virucide. Chang (1) reports that above pH 8, HOI decomposes slowly to form iodide and iodate ions, especially in the presence of dissolved iodides. Neither iodides nor iodates have been found to be germicidal. Further, I.sup.- reacts with I.sub.2 to form the highly coloured I.sub.3.sup.- ion, which is also ineffectual as a germicide.
Various tinctures of iodine may be generated upon dissolving the solid in organic liquids such as ethanol, acetone, diethyl ether, toluene, p-xylene, benzene and carbon disulphide. Additionally, many organic preparations of iodine may be generated by reacting appropriate organics with iodine, e.g., iodoform, methylene iodide. Among the most popular commercial iodine-organic complexes are the PVP-iodines, iodoforms and povidone-iodine preparations, which are used as detergents and antiseptics. Most of these compounds exhibit germicidal action upon dilution in water, whereupon the iodine is hydrated and released into the water, usually as molecular iodine. Many biocidal, organic iodine compounds are commonly referred to as iodophors.
Traditionally, iodine-bearing resins are made by attaching I.sub.2, tri-, penta- and hepta-iodide ions to quaternary ammonium, styrene-divinyl benzene, cross-linked anion-exchange resins. Upon elution with water, the polyiodides and iodine are released from the resin via anion-exchange mechanisms. These resins are thought to operate on a demand-type basis, where iodine will only be released in the presence of a germicidal load in the water passing through the resins, by the following mechanisms; (1) iodine release aided by an internal exchange mechanism involving I.sub.2 transfer through a polyiodide intermediate, (2) hydrolysis of iodine on the resin to produce HOI, (3) simple release of I.sub.2 by the resin-polyiodide combination and/or organic resin matrix.
Disinfection of drinking water for farm animals, particularly, chickens and pigs raised under confined conditions represents a major problem owing to the contamination of the water throughout the entire distribution systems by common bacteria present in animal feces, such as E coli, other fecal coliforms and fecal streptococci. Both pigs and chickens spread the bacteria found in manure from barn floors to drinking vessels, which, in turn, leads to back-contamination of the entire water distribution infrastructure network and allows infection to spread from barn to barn. Further, seasonal variations in source-water bacterial levels have been found to contribute to infection of livestock.
The use of chlorine-based or iodophor products for the disinfection of farm animal drinking water is not very satisfactory and suffers from significant disadvantages.
The following lists show some of the many problems associated with using chlorine or iodophor products for water disinfection.
Chlorine
highly unstable with respect to composition of individual batch lots PA0 causes fatality if dosage exceeds 10-12 ppm PA0 gasses off at higher temperatures to generate toxic aerosols PA0 reacts with naturally occurring acids to form toxic by-products, for example, tri-halomethanes PA0 very sensitive to changes in pH and temperature and is only effective in narrow pH and temperature ranges PA0 moderately-to-highly corrosive depending on its concentration and chemical specification to damage distribution equipment and requires special handling PA0 requires careful pre-mixing, before distribution to livestock PA0 very high maintenance costs for distribution system, and PA0 liberates free chlorine gas upon exposure to most metals. PA0 high levels of phosphoric acid in most commercially available products causes burning of avian digestive tract which results in weight loss and/or fatality, as well as damage to metals and rubber seals within the distribution networks PA0 much more expensive than chlorine products owing to preparation and shipping costs PA0 sensitive to exposure to light and also photo-degradable PA0 biologically active only when mixed with water, if permitted to remain in prolonged storage, undiluted iodophor may develop infection by Pseudomonas spp. bacteria, and this infection can be passed on to animals resulting in infection of entire broods PA0 messy to handle PA0 dilution of raw iodophor must be strictly controlled in order to maintain proper levels of disinfection without poisoning livestock PA0 organic solvents permits moderate degree of gassing-off of iodine. PA0 surface disinfectant in food processing, medical environments, dental offices; PA0 equipment disinfectant in food processing, medical environments, dental offices; PA0 hand wash in food processing, medical environments, dental offices; PA0 foot bath in processing industries; PA0 conveyor belts; PA0 industrial/commercial cooling tower water to adequately disinfect the cooling water prior to discharge or reuse; PA0 carcass wash equipment for meat, poultry and fish with no iodine uptake into the flesh in the food processing industry, to enhance the shelf life of fresh food; PA0 fruit and vegetable wash equipment whereby the disinfection of fruits and vegetables prior to shipping for local or export markets is necessary in most countries around the world; PA0 close loop water recirculation systems in vehicle and other equipment for the transportation of live marine animals and fish and in aquaculture. The iodine species-containing solutions of the invention are provided in controllable specific dosages for both micro-nutrient and disinfection needs; PA0 water chemistry adjusters and post filters to supply microbially safe iodine-free drinking water and to deliver safe drinking water through disinfection and concurrently deliver iodine as a human micro-nutrient to combat Iodine Deficiency Disorder presently affecting millions of people, globally. It may, optionally, be used on a large scale in conjunction with chlorine to create a dual halogen effect for disinfecting drinking water; PA0 deliver specific metered dosages of iodine through a watering system to be used as a soil disinfectant, herbicide and to enrich iodine deficient soil, to address vegetable iodine uptake as well as microbial control in the soil; PA0 specific metered dosages of iodine to aerosol spraying systems for misting livestock during warm weather and fruits and vegetables during transportation and presentation; PA0 to provide metered dosages of pure, elemental iodine in the manufacture of pharmaceuticals; PA0 as an essential iodine additive to most commercial feeds to eliminate the associated costs of the carrier molecule for the iodides as presently used; PA0 for use as iodine containing disinfectant in industrial process water in cooling canals for canned fruits and vegetables and the movement of fish by means of water canals throughout a processing plant or a final rinse in a fresh fruit or vegetable wash canal; PA0 iodine as the sole disinfectant that can control microbes without damaging marine life and, thus, the iodine species-containing water can disinfect ballast water prior to dumping to avoid problems, such as the introduction of Zebra mussels, in consequence of ships carrying contaminated water from one port with subsequent dumping in another port; PA0 as a micro-nutrient for human, animal livestock, fish and plants which require iodine in their diets to sustain growth and good overall health. Present vehicles of delivery for iodine to humans is iodized salt and for livestock animals and fish it is added to their feed as a form of iodide by the spraying or irrigation of plant for them to retain the iodine and pass it on through the food chain in iodine deficient areas of the world. In the case of fish it can be put in feed and or added to the water supply. The system can deliver required metered dosages for human consumption, added to livestock feed during preparation and in the water for marine life; PA0 as an egg wash wherein the movement of commercial eggs often requires disinfection of the egg, and in the case of fish a disinfectant during hatching to reduce mortality. PA0 as an iodine source as a disinfectant in packaged and industrial ice wherein there is presently no disinfectant grade ice product available. Chlorine escapes through the crystal lattice of the ice and iodophor has limited opportunity for success due to the chemical by-products in the iodophor matrix. The system of the invention can provide metered specific dosages of iodine to water supplies feeding all types of ice machines. Different dosages and different ice types are required in the various ice applications. There is no significant iodine uptake by fish fillets in contact with iodinated ice or the resultant melt water; PA0 in sewage and waste water treatment.
Iodophors
In addition to the aforesaid disadvantages of existing disinfectants in the aforesaid farm animal drinking water, other industries and fields requiring the use of disinfectants are subject to similar disadvantages. Industries such as agriculture, fisheries, pharmaceutical, medical and dental field, ship ballast and cooling tower waters, industrial process water and sewage and waste water treatment all suffer from the inadequacies of existing disinfectants, such as chlorine and iodophor as hereinbefore described and quaternary ammonium compounds.
Accordingly, there is a need for a water treatment system which provides drinking water to farm animals through a distribution network by which bacterial levels can be efficaciously controlled and which reduces bacterial back-contamination and for an improved disinfectant for the aforesaid duties as hereinbefore listed.